Cicuta douglasii / water hemlock

Adjectives: clonal, fen, highly visible, invasive, native, poisonous, riparian, toxic, weed, wet meadows

Also known as: beaver poison, fever root, poison parsnip, cowbane, Douglas water hemlock, western water hemlock

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At the outset, it should be said that water hemlock has been called the most poisonous plant in the North America, perhaps even more toxic than the poison hemlock that Socrates so famously drank (and died, not pleasantly). The poison is especially strong from the roots, which is a problem since other members of the carrot family have edible roots. Leaves and stems lose most of their toxicity as they mature; however, green seed heads are poisonous. The plant’s sap containing the toxin turns reddish brown when exposed to air… if you get juice of plant on your hands, wash immediately. Even small amounts can cause death if ingested.

Water hemlock has been confused with wild parsnips, other herbs, and medicinal plants. This is not an OK mistake to make unless you are perhaps already sitting in an emergence room.

Is this clear? OK, given those cautions…

The water hemlock plant is tall-ish, up to 3 feet in the Valley, and the stem has purple spots or stripes. The leaves are once to three-times pinnately compound, often with long spaces between the separate pinnae. The leaflets of Cicuta can be distinguished from similar, non-toxic species in the family by their venation patterns – the veins fork at their tips, with one branch ending at the tip of the leaflet and the others in the notches between leaflet lobes.

Water hemlock roots are thick and tuberous, with many smaller tubers coming from the main tuber. The tubers have significant air spaces, probably an adaptation to living in wet or waterlogged soils. Unless you are wearing gloves when you find this out, go wash your hands!

There are amazingly few descriptions of the water hemlock inflorescence on the web, possibly because it looks so much like other members of the Apiaceae. Basically, the inflorescence is a compound umbel with many small white or creamy white, 5-petaled flowers. The leaves are certainly more useful as an identification tool.

There are two seeds produced by each flower. These also look like the seeds of other Apiaceae. Seed dispersal is by wind, water, machinery, on clothing, and through transported soil. Germination occurs in spring, but in addition to seed propagation, rootstocks also produce new plants.

As for habitat, this perennial herb is found primarily on wet soils, in ditches, on stream banks, pond margins, and in marshes. It is found primarily in continuously wet areas, but also can grow in vernal areas.

This plant has an enormous impact on animals, partly because it appears very early in the spring and has “a very appealing odor”. It takes very little to kill a cow, sheep, horse or pig and death can occur quickly (like within 15 min).